JPH11124251A - Displacement detecting method in sheet transfer system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing device emitting an alarm for operation stop which will be produced in the near future due to displacement of a sheet in a sheet transfer system. SOLUTION: A sheet transfer system 24 included in a printing device 10 is provided with a plurality of sensors S1 to S3 arranged along a sheet transfer path 36, and these sensors detect a sheet moving on the sheet transfer path. It is further provided with a controller 38 which detects the amount and position of a displacement produced on the sheet transfer path by a comparison between the outputs from the plurality of the sensors. After the position of the displacement has been detected, automatic correction by the printing device or manual correction by a service person is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting a jam in an electrophotographic printing apparatus. ) To determine if an event has occurred.

[0002]

2. Description of the Related Art Electrophotographic printing devices typically include a photoconductive member charged to a uniform potential. The charging is performed to impart photosensitivity to the surface of the photoconductive member. The charged photoconductive member is exposed to a light image of the original document to be copied. Thereby, within the area illuminated by the image, the charge of the photoconductive member is selectively released, and an electrostatic latent image is formed. The electrostatic latent image recorded on the photoconductive member corresponds to the image of the original document. next,
A developer material including toner is provided in contact with the photoconductive member and adheres to the photoconductive member in a pattern of latent images to form a toner image. The toner image is then transferred from the photoconductive member to a sheet of material such as paper. Further heating of the sheet fuses or fuses the toner image to the sheet.

[0003] In the electrophotographic printing apparatus described generally above, the sheet on which the image is to be printed is transported to and from the photoconductive member by a sheet transport system. This sheet transfer system generally includes a driving roller constituting a sheet transfer path,
Including idler rollers and / or belt systems. It is important that the sheet move on the sheet transport at a specific timing synchronized with the image forming system and other systems of the apparatus. Many conventional electrophotographic imaging devices use a registration system that registers sheet arrival and / or departure at different sensing locations within the sheet transport system. The registration system detects a jam when the arrival or departure of a sheet is delayed at a certain sensing location. If the arrival or departure of a sheet (called a sensing event) occurs outside of a predetermined jam period or window, the registration system detects the jam. The jam window defines an allowable time range in which a sensing event can occur without a jam determination being made.

[0004] The occurrence of a sensing event outside the jam window that is determined to have a jam may be due to various problems within the sheet transport system. For example,
The sensing event is delayed by the gradual drift or misalignment of the sheets transported in the sheet transport system. The delay of the sensing event due to the offset may not delay the occurrence of the sensing event out of the jam window. However, deviations that have accumulated over time due to continued use and wear of the sheet transport member cause a sensing event to occur outside the jam window and a jam is determined. In a conventional electrophotographic printing apparatus, a gradual advance of a sheet is not detected until the occurrence of a jam is determined and the apparatus is stopped.

[0005] Sheet misalignment during transport is caused by excessive soiling or wear of the rollers and / or belts of the sheet transport system, or improper adjustment of the sheet transport system. However, the occurrence of the deviation is not usually detected until the occurrence of the jam is determined. Therefore,
The problem that caused the gap is that the occurrence of jam is determined,
Not corrected until the device stops.

[0006]

Prior to the stoppage of the apparatus due to jam detection, relatively gradual sheet drift or misalignment in the sheet transport system causing delays in sensing events is required by the service personnel of the apparatus in advance. It is desirable to warn. Service personnel who have received the advance warning will report the problem causing the slip (for example, during periodic inspection).
Correction can be made, and downtime due to equipment stoppage, which may occur thereafter, can be prevented. The operation of the printing device can be queried or monitored, for example, by remote interactive communication (RIC) or by requesting a response from the printing device through non-volatile storage (NVM). Other devices and systems for electronic measurement and communication are of course conceivable.

[0007] It is more desirable to be able to detect in which part of the sheet transport path the misalignment occurs so that the service person can immediately notice the problem.

In the conventional electrophotographic printing apparatus, the occurrence of a jam is determined, and only after the apparatus is stopped, a sheet shift is detected and no advance warning of the shift is issued, so that the cause of the shift is not corrected. There was a problem.

[0009] It is an object of the present invention to provide a new method and apparatus for providing an advance warning of a shutdown that may be due to a sheet shift in a sheet transport system in the near future.

[0010]

According to one aspect of the present invention, a sensing event is sensed at a plurality of consecutive sensing locations along a sheet transport path of a sheet transport system. Detecting the amount of displacement of the sheet between each of the plurality of consecutive sensing positions by comparing the sensing events, and detecting the position of the displacement in the sheet transport system. And correcting the detected deviation. The apparatus and method according to the present invention solves the problem of deactivation due to jam detection by detecting and correcting the deviation of the sheet being transported in the sheet transport system. In the present invention, the position where the deviation has occurred can be detected in order to perform the automatic correction by the apparatus itself or the manual correction by the service person.

In accordance with one aspect of the present invention, a method for detecting misalignment in a sheet transport system of a printing apparatus includes a plurality of initial states representing when a sheet passes a plurality of consecutive sensing locations in the sheet transport system. Detecting; and adjusting the plurality of jam windows such that one of the plurality of initial states is arranged in each of the plurality of jam detection windows at a predetermined position; and sensing at each of the plurality of continuous sensing positions. Sensing an event, detecting a sheet shift at a plurality of consecutive sensing locations in the sheet transport system, and correcting the detected shift.

According to another aspect of the present invention, a printing apparatus or apparatus includes a sheet transport system that advances individual sheets along a sheet transport path by frictional contact with a plurality of drive members. The plurality of sensors are provided along the sheet transfer path, and detect a sheet moving on the sheet transfer path. The controller compares the outputs from the plurality of sensors to detect the amount and position of the shift occurring on the sheet transport path.

According to still another aspect of the present invention, an automatic deviation correcting mechanism corrects a deviation of a sheet in a sheet transport path.

A major advantage of the present invention includes the ability to sense a gradual drift or misalignment of a sheet being conveyed within the sheet conveying apparatus prior to shutting down the printing apparatus. An advantage of the present invention is also the ability to detect where drift or misalignment has occurred.

[0015] A further advantage of the present invention is the ability to correct for sheet misalignment prior to shutting down the printing device.

[0016] Other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading and understanding the following description of embodiments.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS The invention may take, in certain parts or combinations of parts, the form of the embodiments described in detail below in this specification and the accompanying drawings.

Although the present invention will be described below with reference to preferred embodiments, the present invention is not limited to those embodiments.

FIG. 1 shows an electrophotographic printing apparatus having the features of the present invention. The electrophotographic printing device 10 generally includes
Document handling unit 14, photoconductive member 16, corona charger 1
8, an image forming system 12 having an exposure position 20, and a development position 22. A sheet transfer system 24 is provided for transferring sheets on which images are printed from one or more sheet storage trays 26 to the photoconductive members 16.
Thereafter, the sheet is transferred to the sheet receiving tray 28.

The sheet transport system 24 typically transports individual cut sheets by a series of drive rollers 30, idler rollers 32, and / or belts 34. The sheet transport system 24 forms a sheet transport path 36 along which sheets are transported by the controller 38 according to a specified schedule coordinated with other systems of the electrophotographic printing apparatus. Soil, wear, and / or deterioration of the roller and / or belt elastomer in the sheet transport system may cause a gradual drift or slippage, thereby delaying the arrival of the sheet at a sensing location. . The sensing positions include sensors S1-S3 provided at pre-selected positions along the sheet transport path 36, which can detect where the sheet is located on the sheet transport path. The quantity and position of the sensors S1-S3 can be changed according to the individual situation of the sheet transfer path 36.

The jam windows A, B, and C in FIG. 2 correspond to a plurality of sensing positions along the sheet transfer path, such as the sensors S1 to S3 shown in FIG. In conventional systems, sensing events A2, B2, and C2, which indicate sheet timing or position, are sensed. Sensing events are usually
The timing or arrangement of a leading edge or a trailing edge of a sheet at one of a plurality of sensors S1-S3 along the sheet transport path.

As long as the sensing events A2, B2, C2 occur within each jam window A, B, C, the printing device continues to operate. However, if an error such as a sheet shift occurs and the sensing event occurs outside one jam window, the occurrence of the jam is determined, and the printing apparatus is deactivated. Here, the jam windows A, B, and C are S1-S
Representing any of the three sensors, more or fewer sensors and jam windows can be used to accurately monitor misalignment in the printing device. Further, it will be apparent from the following description that the jam windows A, B, and C represent continuous windows. A shift in the upstream jam window (for example, the jam window B) is also detected in the downstream jam window (the jam window C). Further shifts occurring between the two jam windows are also detected in the windows downstream thereof. As described above, when the accumulation of the deviation within the allowable range is detected as being compounded and detected outside the jam window in the downstream jam window, the operation is stopped as a result.

According to the present invention, the jam windows A,
The positions of B and C are adjusted so that each sensor S1-S3 allows a predetermined amount of shift. Due to mechanical fluctuations in the sheet transfer path, such as slight fluctuations in roller diameter,
There may be differences in the position of the sheet at certain points in different devices. The jam window is adjusted or calibrated prior to using the device to maximize device performance and address manufacturing variability. As shown in FIG. 3, the jam windows A, B, and C are initialized such that the sensing events A3, B3, and C3 are closer to the front edge (left side) than the rear edge (right side) of each jam window. . Sheets transferred by the sheet transfer device cannot move faster than the feed speed and, in many cases, slow down due to misalignment. Therefore, by arranging the leading edge of the jam windows A, B, and C rather than the trailing edge at a position adjacent to the sensing event, each of the sensors S1-S3.
, An allowable range of deviation is provided, and unnecessary stoppage of the device is avoided.

The adjustment of the jam windows A, B, C according to the invention as shown in FIG. 3 is preferably performed electronically by the manufacturer. This adjustment may be part of a series of inspections of the printing device performed by the manufacturer as part of product management before shipping to the customer. After the printing device is installed at the installation location of the customer, the jam window may be adjusted again if necessary. Comparing FIG. 2 showing before the adjustment of the jam windows A, B, and C with FIG. 3 showing the state after the adjustment, the adjustment can prevent unnecessary stoppage of the apparatus which can occur when the initial state is near the rear edge of the jam window. I understand. For example, in FIG. 2, the sensing event B2 is shifted to the right end of the jam window B. In this case, if a slight displacement occurs in the transferred sheet at a position corresponding to the jam window B on the sheet transfer system, the apparatus stops. On the other hand, as shown in FIG.
Is adjusted to the right, sensing event B3 is positioned closer to the front edge of the window, and premature stoppage of the device as described above is avoided.

FIG. 4 shows the occurrence of deviation during sheet transfer. According to FIG. 4, the sensing event A4 occurring in the jam window A has not yet shifted from the initial state A3 of FIG. However, the sensing event B4 occurring in the jam window B is shifted from the initial position B3 of the sensing event.
The amount of displacement that has occurred between window A and window B, the next sensing location, is measured as the distance between B3 and B4 and reported by the controller. By clarifying the amount and location of the shift, service personnel can identify and correct the cause of the shift.

FIG. 4 further shows a sensing event C4 and a sensing event C5. Any of these sensing events can occur at the location of jam window C. C3 and C
Since the distance between 4 is the same as the distance between B3 and B4, the location of sensing event C4 indicates that no further displacement has occurred at the corresponding location between jam windows B and C. On the other hand, the location of sensing event C5 indicates that an additional shift has occurred at a location corresponding to between jam windows B and C.

The amount and position of the deviation detected as described above is monitored and reported by the controller 38. The information provided by the controller 38 is used to inform a service representative that service is required before the shift reaches the outside of the jam window. As a result, a warning to stop the operation of the printing apparatus is issued while the operation can be continued with only a slight adjustment.
Information from the controller 38 is transmitted via remote interactive communication (RI
It may be transmitted electronically to a remote location by conventional methods such as C). The information is also stored in a non-volatile storage device (NV
M) and may be read out by a service person or a service company at the time of periodic inspection or the like. The service technician can correct the problem that caused the misalignment, for example, by replacing worn rollers or cleaning dirty parts.

Controller 3 for specifying displacement amount and position
The information from 8 can also be used to automatically make temporary or permanent misalignment corrections. Automatic correction of the misalignment may be performed by adjusting operation commands provided to the sheet transport system 24. For example,
By increasing the speed of one or more rollers or belts in a particular area of the sheet transport system, the feed speed can be increased and the sheet advanced with the required continuous timing. Or, the sheet storage tray 26
The sheet can be supplied at an earlier timing from one of them, and the deviation detected behind (or downstream) of the sheet transfer path 36 can be corrected. Another method of auto-correction is
The use of a servo system to accelerate the sheet at a particular location where misalignment has occurred in the sheet transport system and realign the sheet to the required location.

A subsequent jam window may be adjusted as an adjustment for the shift that occurs between the two sensing positions along the sheet transport path 36. Adjusting the jam windows downstream of the position where the shift occurs can prevent the detection of jams due to the accumulation or stacking of the shifts at the positions corresponding to those windows. For example, if there is a large shift between jam windows A and B, jam window C and all subsequent jam windows are moved to the right by the amount of shift between jam windows A and B. Thereby, the operation stop of the apparatus is avoided until the service person removes the cause of the gap between the jam windows A and B.

The information about the offset provided by the present invention may allow the device itself to perform the correction completely, or the device itself may perform the correction to a level sufficient to continue operation at a lower throughput. In addition, the operation of the device can be avoided. As one method of the automatic correction, it is conceivable to reduce the ratio of the number of executions of the processing by reducing the number of the equally-spaced images while maintaining the same processing speed (skipping pitches). For example, if the stapler can no longer maintain maximum yield, the device can reduce the number of equally spaced images from five to four.

Some of the automatic corrections described above are usually temporary measures, which allow the service to continue until the device is repaired. When a service technician repairs the device by cleaning the sheet transport system or replacing worn or dirty parts thereof, the jam window is removed according to the method described in connection with FIG. Automatic adjustment is desirable.

The detection of a sensing event in the present invention is performed in a conventional manner. That is, sensors S1-S3 are used in conjunction with device clock information to detect when the leading or trailing edge of a sheet passes a particular sensing position.

The present invention is applicable to an apparatus having a long sheet transfer path, in which a small amount of errors may cause a serious problem for jam detection on the downstream side even if the errors accumulate in small amounts.
Most effective.

Advantages of the system according to the invention include the ability to identify the origin or area of the deviation on the sheet transport path. In a conventional jam detection system, occurrence of a jam is often determined in any of the downstream portions of the sheet transport path based on the accumulated deviation. In a conventional system, for example, it is assumed that a relatively large deviation has occurred in the upstream portion of the sheet transfer path, although it does not reach the jam determination. In that case, if a small deviation occurs several times in the downstream part,
A jam decision is triggered. The present invention provides a method for detecting at which position the shift actually occurs, ie, between S1 and S2 or between S2 and S3. This provides an opportunity to perform an automatic correction or a more thorough inspection of the area identified as having an abnormally large deviation by the service personnel. Obviously, any number of sensors may be used, and the position of the shift can be detected more accurately by increasing the number of sensors.

The offset data provided by the present invention is also useful for identifying sheet transport system designs that minimize offset.

The present invention has been described above with reference to a preferred embodiment. Obviously, modifications and alterations can be made in the light of reading and understanding this specification. All such modifications and changes are intended to be included herein insofar as they come within the scope of, or follow, the claims.

[Brief description of the drawings]

FIG. 1 is a schematic front view illustrating an electrophotographic printing apparatus including a sheet transport system according to the present invention.

FIG. 2 is a schematic diagram illustrating three jam detection windows and three sensing events that occur within the jam detection windows.

FIG. 3 is a schematic diagram illustrating three jam detection windows adjusted based on three initial sensing events.

FIG. 4 is a schematic diagram illustrating three jam detection windows and sensing events illustrating the occurrence of a shift.

[Explanation of symbols]

Reference Signs List 10 electrophotographic printing apparatus, 12 image forming system, 14 document handling section, 16 photoconductive member, 18
Corona charger, 20 exposure position, 22 development position, 24
Sheet transfer system, 26 sheet storage tray, 28
Sheet receiving tray, 30 drive roller, 32 idler roller, 34 belt, 36 sheet transfer path, 38
Controller, S1-S3 sensor, A2-A4, B2
B4, C2-C5 sensing events.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Jerry Kay Whitfill Jr. Arlington & Meadow Park Drive Texas 4119 United States of America

Claims (1)

[Claims] 1. A method for detecting a shift in a sheet transport system of a printing apparatus, comprising: sensing a sense event at a plurality of consecutive sensing positions along a sheet transport path of the sheet transport system; Detecting the amount of deviation of the sheet between each of the plurality of consecutive sensing positions by comparing; detecting the position of the deviation in the sheet transport system; and detecting the detected deviation. Modifying.